Preparation of insoluble polyvinylpyrrolidone

Abstract

Insoluble cross-linked homopolymers of vinylpyrrolidone or copolymers of vinylpyrrolidone are prepared by reaction of the soluble homopolymer or copolymer with certain acid chlorides at a temperature between 75° C. and about 140° C., to obtain a precipitate. Alternately, the insoluble product may be prepared by heating a partial amide chloride of a homopolymer or copolymer of vinylpyrrolidone.

I claim: 
     
       1. A process for the preparation of insoluble homopolymers or copolymers of vinylpyrrolidone which comprises refluxing uncross-linked polyvinylpyrrolidone or an uncross-linked copolymer of vinylpyrrolidone with an acid chloride selected from the group consisting of phosgene, and oxalyl chloride in a liquid medium at a temperature between about 75° and about 140° C., to obtain a precipitate of cross-linked polyvinylpyrrolidone or of a cross-linked copolymer of vinylpyrrolidone. 
     
     
       2. A process according to claim 1 in which the liquid medium is a solvent for the acid chloride. 
     
     
       3. A process according to claim 2 in which the solvent is also a solvent for the polyvinylpyrrolidone or the copolymer of vinylpyrrolidone. 
     
     
       4. A process according to claim 1 in which the acid chloride is phosgene. 
     
     
       5. A process according to claim 1 in which the reaction temperature is from 90° to 120° C. 
     
     
       6. A process according to claim 1 in which the acid chloride is oxalyl chloride. 
     
     
       7. The product of the process of claim 1. 
     
     
       8. The product of the process of claim 4. 
     
     
       9. The product of the process of claim 6.